A typical architecture for an existing high capacity MSC server is a server structure having a blade cluster structure with a plurality of blades. Transmission lines that carry payload are terminated in media gateways (MGw). The switching of these resources is controlled by the MSC server (MSC-S).
Time division multiplex terminations (TDM terminations) as they are used in contemporary telecommunication systems are not well-suited to be controlled by a blade cluster server because neither the call control signaling nor the media gateway control signaling provides support for a multi-blade architecture. Before a resource such as a termination can be used for a call, coordination of exclusive usage must be performed between the different blades of the switching center server. Furthermore, signaling messages need to be routed to the blade that handles the respective call.
Ephemeral terminations are better suited for a multi-blade architecture. The seizure of termination is coordinated by the media gateway. There is no need for inter-blade coordination on the MSC server side. Signaling messages need to be routed to the blade that handles the respective call. BICC (bearer independent call control) uses ephemeral terminations but requires coordination of call instance codes (CIC) on the MSC server side since they are a common resource of all blades.
With the above-described technology, it is difficult to share TDM terminations and CICs amongst several blades. The range of available TDM circuits and for BICC the range of call instance codes has to be partitioned. In this case, each partition is administratively assigned to a particular MSC server blade.
However, the partitioning of resources has the drawback that the partitioning inhibits the efficient use of user plane circuits. If a blade fails, the resources that are dedicated to a failing blade are unavailable for other traffic. Furthermore, it is more difficult to configure the MSC server compared to a system that does not need to partition the TDM circuits. Especially when blades are added or removed from the cluster, re-partitioning of the resources assigned to the other blades needs to be performed. The number of blades in active state can change for example due to outage of individual blades or in case the server performance is increased by adding new blades. If the number of circuits to be partitioned is only little higher than the number of blades, even distribution of connectivity to the blades becomes difficult. If there are fewer circuits to be partitioned than there are blades in the cluster, connectivity cannot be provided to all blades.